石墨烯/聚酰亚胺介电复合材料的制备与性能

采用密闭氧化法制备氧化石墨,经过超声分散剥离得到氧化石墨烯(graphene oxide,GO),然后以聚乙烯吡咯烷酮为保护剂、维生素C(Vc)为还原剂,在N,N-二甲基甲酰胺溶液中还原氧化石墨烯,得到还原状态的石墨烯(reduced graphene oxide,rGO),最后采用原位复合、流涎成膜方法制备石墨烯/聚酰亚胺(rGO/PI)复合薄膜。利用傅里叶变换红外光谱仪(Fourier transform infrared spectroscopy,FTIR)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱仪(X-ray photoelectron spectrograph,XPS)、热重分析/差式扫描量热分析(TGA/DSC)等多种表征方法对rGO和rGO/PI复合薄膜的形貌、结构和热稳定性进行分析,用宽频介电谱仪测试复合薄膜的介电性能。结果表明,rGO是一种高效的导电填料,极少的添加量即可显著提高PI的介电常数,且对PI的其它性能影响较小。rGO/PI复合薄膜的介电常数随rGO填料含量的变化规律符合逾渗阈值模型,逾渗阈值f0为0.461%,临界指数q为0.523。当rGO含量(质量分数)为0.7%时,薄膜的介电常数为35.1,是纯PI的8.4倍。     

三维自支撑的铜铋双金属电沉积制备及其电催化还原CO2性能研究

金属铜(Cu)是二氧化碳(CO₂)还原为甲酸的常见催化剂,但是存在竞争析氢副反应(HER)严重和稳定性差等问题。引入第二金属的合金化策略可以有效改善上述问题,但是复杂的合成方法限制了电催化CO₂还原技术中的实际应用。鉴于此,开发了一种简单、快速、低能耗的原电池沉积法,以还原电势差为反应驱动力,通过调节前驱体浓度在石墨烯基底上原位生长具有三维自支撑结构的铜铋(CuBi)双金属纳米枝晶(nCuBi-G/Cu foil)。研究表明：nCuBi-G/Cu foil结构中Bi作为电子供体向Cu提供电子,从而增加Cu中心电子密度,可以有效抑制CO₂RR过程中的析氢反应,大幅提高甲酸产物的选择性,并且降低了电极表面的积碳浓度,提高CO₂电催化反应的稳定性。此外,石墨烯导电基底可以加速CuBi和基底之间电子传递过程,改善CO₂催化过程动力学,提高CO₂RR活性。基于以上效应,nCuBi-G/Cu foil表现出95.9%的甲酸选择性,并且在此电压下可以稳定运行20 h,且...     

氧化石墨烯/氧化铕复合粉体的制备及性能研究

以氧化石墨烯和氧化铕为原材料,利用水热法合成了氧化石墨烯/氧化铕复合粉体。对不同氧化石墨烯加入量的复合粉体采用扫描电镜、差热分析、荧光分析等测试方法对其进行表征。结果表明:利用水热合成的方法成功制备了氧化石墨烯/氧化铕复合粉体;氧化铕包裹在氧化石墨烯表面,阻止了氧化石墨烯表面部分官能团的分解,复合粉体的稳定性较好;由荧光激发光谱可知复合粉体的荧光激发波长为435 nm;由荧光发射光谱可知,随着氧化石墨烯的质量分数从6%增大到10%时,复合粉体的荧光强度依次增强。     

异原子配位结构碳基单原子电催化剂结构与性能相关性的研究进展

单原子催化剂（SACs）由于其原子利用率高、活性中心明确、比活性高和稳定性强等优点,在催化电解水领域具有独特的优势. 然而,材料中的金属−载体相互作用对催化过程具有重大影响. 首先,本文明确了单原子催化剂的特点并研究了其电子结构和构效关系方面独特优势. 其次综述了氧化物载体在稳定金属单原子、分散活性物种、调节中心电子结构、吸附和活化反应物等方面的重要作用;并详细分析了载体如何通过结构缺陷、表面基团、空间限域和晶格作用等实现对金属原子的负载和稳定. 然后,通过实例对比了单原子在不同氧化物载体上配位结合方式,以及在析氢、析氧和全水解反应中的性能差异. 最后,对利用载体与单原子相互作用调节催化剂性能的机遇和挑战、关键问题和可能的解决方案进行了展望.

     

粉末冶金法制备石墨烯/2024Al复合材料的组织及性能研究

本文以石墨烯纳米片和2024Al合金粉末为原材料,利用冷等静压+真空烧结+热挤压的方法制备了不同质量分数的石墨烯/2024Al复合材料,通过对复合材料进行SEM表征、能谱分析以及力学性能测试,研究了不同质量分数石墨烯/2024Al复合材料微观组织和宏观性能。结果表明：经过冷等静压+烧结后的石墨烯/2024Al复合材料中石墨烯呈现随机分布,此时致密度较低。通过热挤压后,能够使石墨烯呈定向排列,且显著提高复合材料的致密度。0.5%和1%挤压态石墨烯/2024Al复合材料的抗拉强度可分别达到290.6 MPa和321.1 MPa,相比基体分别提高了48.8%和64.4%,表明石墨烯的引入以及质量分数的增加能显著提高复合材料的抗拉强度。     

V_2O_5/RGO纳米复合材料的制备及表征

通过简单的一步水热反应制备出V_2O_5/RGO纳米复合材料。采用XRD、SEM及电化学工作站对其结构、形貌和电化学性能进行了分析表征。结果表明,V_2O_5/RGO纳米复合材料中V_2O_5晶型为斜方晶相,复合材料中V为V＋4、V＋5两种价态,且V_2O_5/RGO的形貌为片状结构,该纳米复合材料在0.5mol/L K2SO4电解液中以5m V/s进行CV测试时,比电容可达208.04 F/g,而且其电化学窗口可以达到1.6V（-0.6~1.0V）,表明V_2O_5/RGO纳米复合材料有望成为一种潜在的超级电容器电极材料。     

氧化石墨烯/壳聚糖复合微球的制备及其对铌的吸附性能

实验采用改进Hummers法合成了氧化石墨烯(GO),再用壳聚糖(CS)与GO制备了交联壳聚糖微球(GCCS)和GO质量分数分别为2%、5%、10%的氧化石墨烯/壳聚糖复合微球(GOCS),对其进行了表征,并研究了其对Nb的草酸配合物的吸附性能。结果表明,在1mmol/L的H_2C_2O_4溶液介质中,优化的吸附条件为GOCS中GO的质量分数为5%、pH=3。该吸附反应符合Langmuir等温吸附模型,为单层吸附,理论最大吸附量为38.46mg/g。动力学实验表明,该吸附反应符合准二级动力学模型。热力学实验表明,该吸附反应为自发反应、放热反应。采用5mL 1mol/L的HNO_3溶液进行洗脱实验,洗脱率为84.9%。3次吸附洗脱循环实验,吸附率和洗脱率并未出现明显下降,表明再生性能良好。     

高效V-Cr-Mo-O/SiO2催化剂的制备及应用--氨氧化合成酞腈新工艺

气相氨氧化邻二甲苯合成酞腈 (邻苯二甲腈 )是目前最简便、最经济的合成工艺。针对邻二甲苯的特点 ,开发成功选择性高、寿命长、氨与邻二甲苯的物质的量之比 (A2 )较小的新型V -Cr-Mo-O/SiO2 催化剂。经流化床中试生产结果证明 :邻苯二甲腈重量收率可达 78% ,产品纯度≥98% ,达到了发达国家水平     

含氧复合型Pt/C催化剂的制备、表征及其对甲醇电氧化催化性能的研究

利用亚锡酸对氯铂酸的弱的多步骤还原制备新型Pt/C催化剂.用XRD、HRTEM、EDS、DSC以及氢吸附电化学对所制备的催化剂进行了表征,并用循环伏安和恒电位极化对其进行了甲醇电氧化催化活性测定.实验结果表明,应用亚锡酸法合成的Pt/C催化剂具有很高的甲醇电氧化催化活性,在0.5V(SCE)电位下,其质量活性约为亚硫酸路线合成的Pt/C催化剂的2倍.亚锡酸法可在纳米尺度范围内生成金属Pt和Pt氧化物共存的复合型碳载催化剂,这种含氧复合型催化剂可以促进Pt在甲醇电氧化过程中双功能作用的有效协调.     

两步水热法制备纳米花状Ni3Fe/Ni3S2高效电催化剂促进碱性电解水析氧反应

分别以Fe(NO₃)₃·9H₂O和Na₂S·9H₂O作为Fe源和S源,用镍网(nickle mesh,NM)作为Ni源与支撑基底,采用两步水热法合成Ni₃Fe/Ni₃S₂析氧催化剂,通过X射线衍射、X射线光电子能谱、扫描电镜和透射电镜分析催化剂的显微组织与形貌,用电化学工作站进行电化学性能测试。结果表明：两步水热法合成的Ni₃Fe/Ni₃S₂催化剂为丰富立体的纳米花形貌,这种形貌可提升催化剂的空间利用率。Ni₃S₂暴露出高折射率的{210}晶面,与Ni₃Fe的(111)晶面产生协同效应,从而提升了催化活性。在1 mol/L的KOH溶液(25℃)中,10 m A/cm²电流密度下Ni₃Fe/Ni₃S₂     

Preparation and application of iron oxide/persimmon tannin/ graphene oxide nanocomposites for efficient adsorption of erbium from aqueous solution

Rare earth elements (REEs) are used for the development of new energy materials owing to their intrinsic physicochemical property. However, excess REEs in water threaten the safety of animals, plants and humans. An efficient way to separate REEs from the water is therefore needed. In this study, a biosorbent consisting of iron oxide (Fe₃O₄), persimmon tannin (PT), and graphene oxide (GO) as Fe₃O₄/PT/GO was prepared, and the adsorption of trivalent erbium (Er³⁺) ions from aqueous solution was investigated. The adsorption process for Er³⁺ ions conforms to pseudo-second order kinetic and the Langmuir isotherm model behavior. Thermodynamic studies indicate that the adsorption process is spontaneous and endothermic. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) analysis, and vibrating sample magnetometer (VSM) were used to assess the adsorption mechanism of Er³⁺ ions onto the Fe₃O₄/PT/GO biosorbent. A combination of electrostatic interactions, redox reactivity and chelation are responsible for adsorption of Er³⁺ ions on the Fe₃O₄/PT/GO biosorbent. The magnetic Fe₃O₄/PT/GO biosorbent can be easily separated under the magnetic field for effective recycle of Er³⁺ ions from aqueous solution. Therefore, this new biomass composite holds great promise for wastewater treatment.     

电解水阳极析氧替代反应及高效催化剂研究进展

开发先进的电解水制氢技术,推动制氢产业规模化发展,是缓解当前能源危机和环境污染的有效途径. 当前发展的电解水制氢技术存在析氧反应(OER)动力学缓慢、能耗高、O₂附加值低、活性氧物种降解隔膜等问题,限制了电解水制氢的大规模应用. 对电解水系统进行反应设计,以热力学上更易发生的阳极反应替代能垒较高的OER,降低过程能耗的同时,得到高附加值的氧化产品,具有显著的经济效益和发展潜力. 本文系统综述了牺牲剂氧化反应(Sacrificial agent oxidation reaction, SAOR)和电化学合成反应(Electrochemical synthesis reaction, ESR)在OER替代研究中的最新进展,对这两大类替代反应进行了分类,重点讨论了它们的氧化机制、适用的非贵金属基催化剂及相应的调制策略. 此外,对开发高性能催化剂助力低能耗混合电解水制氢系统可能面临的挑战和未来的发展方向进行了展望.

     

可光降解聚丙烯/黏土纳米复合物的制备与表征

通过溶胶-凝胶法将锐钛矿型纳米二氧化钛负载到有机黏土片层表面,然后与聚丙烯（polypropylene,简称PP）熔融其混制备可光降解的聚丙烯／黏土复合物。实验结果表明,纳米锐钛矿型二氧化钛粒子均匀分布在有机黏土片层表面,粒子尺寸在8～12nm之间。采用FT-IR,SEM和GPC表征聚丙烯／黏土纳米复合薄膜光降解,结果表明负载纳米锐钛矿型二氧化钛的有机黏土对聚丙烯的光降解速率较商品二氧化钛的快,纳米二氧化钛粒子在有机黏土表面均匀分布,可有效避免二氧化钛粒子的团聚,增加了二氧化钛和聚丙烯基体的有效接触面积,极大地提高了材料的光降解速率。本方法为制备新型环境友好聚合物纳米复合物提供了实验依据。     

Preparation and properties of bifunctional Gd2O3/GQD composite nanoparticles

Nanocomposites of graphene quantum dots (GQDs) modified gadolinium oxide (Gd₂O₃) particles were successfully synthesized. In addition, the effects of the amount of GQDs and the particle size of Gd₂O₃ on the properties of nanocomposites were investigated. The structures and properties of nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence spectrometry, and magnetic resonance imaging. The results show that the synthesized particles Gd₂O₃/GQD are spherical with a diameter of approximately 40 nm and have excellent fluorescence and magnetic property, and its relaxation rate (r₁ = 25.18 (mmol/L)^?1/s) is higher than that of the typical commercial contrast agents Gd-DTPA (r₁ = 4.5 (mmol/L)^?1/s). The fluorescence property of Gd₂O₃/GQD is optimized by varying the V_GQDs:V_Gd2O3 ratio, and 1:1 ratio of V_GQDs:V_Gd2O3 results in the best fluorescence property. The large particles of Gd₂O₃ improve the relaxation property of nanocomposites. Therefore, the nanocomposites Gd₂O₃/GQD with magnetic and fluorescence characteristics can be used in biological imaging, drug targeting, and in-vivo diagnostic analysis.     

Preparation and control mechanism of anisotropic Sm-Pr-Co/Co nanocomposites with unusual continuous soft-phase coatings

To produce nanocomposite materials with high magnetic properties, studies concerning nanostructural processing technologies and control mechanisms are urgently required in aspects of achieving perfect alignment of the hard phase while keeping desired sizes and distributions of the soft phase. In the present study, a designed low-rate electroless deposition method is found to be an effective way in producing strong textured anisotropic Sm-Pr-Co/Co nanocomposites with unusual continuous soft-phase coatings when assembling Co particles on the ball-milled anisotropic Sm-Pr-Co hard phase. The average particle size of the soft-phase coatings is 18–50 nm and the obtained Sm-Pr-Co/Co composites exhibit a high intrinsic coercivity of H_ci = 748 kA/m with an enhanced remanence of M_r = 79 A·m²/g, as compared to H_ci = 836 kA/m and M_r = 68 A·m²/kg for uncoated Sm-Pr-Co hard phase. Moreover, the coating process study reveals a nucleation control mechanism for the formation of the continuous coating structures. Down-sized Sm-Pr-Co/Co nanocomposites with tailored size below 300 nm or even below 100 nm were also produced by this designed method. This study is of theoretical and practical importance for developing advanced nanostructures including the next generation permanent magnets.     

Strategic consultation: The evolution and application of an efficient approach.

Examines how strategic therapy principles can be applied to consultation practice. These principles focus on a conceptual shift in thinking about a problem and its solution, which allows of more effective and often more innovative solutions to consultation problems. In the 1st principle, failed attempted solutions are seen as reinforcing and maintaining problems. The 2nd principle is the notion that it is necessary to develop solutions that implement 2nd order change. The 3rd concept proposes that it is important to change the consultee's perceptions of the problem in order to assist in developing and implementing new solutions. These principles of strategic consultation can also be applied in many settings and can be incorporated in many other consultation approaches. These principles focus on a conceptual shift in thinking about problems and their solutions. This shift allows for more effective, efficient, and often more innovative solutions to consultation problems. A step-by-step procedure is presented. A case example demonstrates how the approach can be implemented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation and application of ZnO doped Pt-CeO2 nanofibers as electrocatalyst for methanol electro-oxidation

ZnO doped Pt/CeO₂ nanocomposites were prepared by electrospinning and reduction impregnation. X-ray diffraction (XRD), transmission electron microscopy (TEM), energy disperse spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the nanocomposites. It is observed that ZnO and CeO₂ form the hexagonal wurtzite phase and cubic fluorite phase in the nanocomposite, respectively, whilst Pt nanoparticles (NPs) with the number-averaged size of ca. 3.1 nm are uniformly distributed on the surface of nanofibers. The mass fraction of Pt NPs in the nanocomposites is about 10 wt%. The doping of ZnO is effective to promote reactive oxygen species, surface reaction sites and the interaction between Pt and oxides. The catalytic performance of nanocomposites was evaluated by the methanol electro-oxidation, indexed with the catalytic activity, stability of catalyst. As a result, it is found that the nanocomposite exhibits much higher activity and stability for methanol oxidation than the undoped Pt/CeO₂ catalyst.     

高温氢还原法制备纳米硅/石墨烯复合材料的结构与电化学性能

将Hummers法制备的氧化石墨烯(graphene oxide,GO)与纳米硅粉进行超声复合和高温氢还原,制备锂离子电池用纳米硅/石墨烯(Si/G)复合材料。利用扫描电镜、透射电镜、X射线衍射和Raman光谱分析,对Si/G复合材料的形貌与结构进行分析与表征,并测试其电化学性能。结果表明,通过高温氢还原,氧化石墨烯全部还原为石墨烯,无其它杂质相生成。石墨烯包覆在纳米硅颗粒表面,形成层状复合结构;与纯纳米硅粉相比,Si/G复合材料的电化学性能明显提高,在300 m A/g电流密度下,首次放电比容量为2 915.0(m A·h)/g,首次充电比容量为1 080.5(m A·h)/g,20次循环后比容量稳定在969.6(m A·h)/g,库伦效率为99.8%;而纯纳米硅粉的首次放电比容量和首次充电比容量分别为932.7和349.4(m A·h)/g,20次循环后比容量仅为6.4(m A·h)/g。